In recent years, liquid crystal display (LCD) devices are inseparable with daily life, and the main requirements for LCD devices are wide angle, high contrast, fast screen switching, low power consumption and stable images, wherein one of the problems of the stable images need to be improved is image sticking.
Liquid crystal reactive monomers (RMs) are added to increase the returning force of the liquid crystal molecules so as to improve the image sticking issue, and thus is applied to LCD devices. However, the solubility of the current liquid crystal RMs in liquid crystal matrix is low, and the curing speed thereof is low, so that the improvement of the image sticking is limited.
More specifically, to increase the returning force of the liquid crystal molecules, liquid crystal RMs having hard core and represented by the formula (III) are added into the liquid crystal composition.

wherein, A is the hard core which contains at least one benzene ring; R1 and R2 are polymer groups, and R1 and R2 are the same or different groups; X is selected from H, F, Cl, CF3 and a straight-chain or branched-chain alkyl group. Referring now to Tab. 1, different performance of different liquid crystal RMs with different volume of hard core is shown in Tab. 1. The experiment shows that the returning force of the liquid crystal molecules relates to the volume of hard core of liquid crystal RMs, that is, the larger volume of the hard core is, the greater returning force of the liquid crystal molecules and the better improvement of the image sticking are. However, the solubility of the liquid crystal RMs in liquid crystal matrix will be reduced if the volume of the hard core is simply increased.
TABLE 1different performance of different volume of hard corethe solubility ofliquidbenzene ringimagethe liquid crystalcrystalnumber of thecuringstickingRMs in liquidRMhard corespeedphenomenoncrystal matrixRM11lowerworsefairRM22fairfairfairRM33higherbetterlower
As a result, it is necessary to provide new liquid crystal RMs to solve the above-mentioned problems existing in the conventional technologies, and to increase the returning force and polymerization capacity of the liquid crystal molecules.